Electric burglar-alarm.



No. '775,723.' PATENTED NOV 22, 1904'.

- A. GETTO.

ELECTRIC BURGLAR ALARM.

APPLICATION IILEDAHL 27,1904.

N0 MODEL.

H 0 T M V N I WITNESSES v ATTORNEYS Patented November 22, 1904;.

UNTTED STATES PATENT @rricn.

} AMOS GETTO, OF NEW YORK, N. Y.

ELECTRIC BURGLAR-ALARIVI.

SPECIFICATION forming part of Letters Patent No. 775,723, dated November22, 1904.

Application filed April 27 1904. Serial No. 205,079- (No model.)

To all whom, it n'uty concern:

Be it known that I, AMos Gn'r'ro, a citizen of the United States, and aresident of the city of New York, borough of Manhattan, in the countyand State of New York, have invented a new and Improved ElectricBurglar- Alarm, of which the following is a full, clear,

and exact description.

My invention relates to electric burglaralarms, my more particularobject being to produce a simple, cheap, and compact alarm to be securedupon the spindle of a door-knob and capable of use also as anannunciator.

Reference is to be had to the accompanying drawings, forming a part ofthis specification, in which similar characters of reference indicatecorresponding parts in all the figures.

Figure 1 is a view, partly in section, upon the line m of Fig. 3 lookingin the direction of the arrow and partly in elevation, showing myinvention as applied to a door-knob spindle. Fig. 2 is a somewhatsimilar view showing the spindle as partially turned. Fig. 3 is a sideelevation showing the device as it would be seen from the left of Fig.1, and Fig. 4: is a diagram of the circuit.

The inner door-knob is shown at 5 and the common spindle of the innerand outer knobs at 6, these parts being of the usual construction. Atwo-part clamp 7 is provided with a hinge 8 and a stem 9, pivoted atoneend to one of the members of the clamp and which swings into a slot 9in the other member of the clamp, and is provided with a thumb-nut forsecuring the clamp rigidly upon the spindle 6. A plate 10 is rigidlyconnected with the clamp 7 and depends therefrom, normally occupying theposition indicated in Fig. 1. This plate 10 is provided with a centralslot 11 and with an ancillary slot 12. A pawl 13 of substantiallydumb-bell shape is free to move relatively to both slots, as indicatedby full and dotted lines in Figs. 1 and 2. The lower end of the plate 10is provided with a pin 14, having a spacing-nut 15 mounted thereon.Pivotally mounted upon this pin and depending therefrom is astrap 16 forsupporting the battery 23 and the bell 24. A disk 17 of insulatingmaterial, is also mounted upon this pin. A nut 18 secures the outer endof the pin, being preferably threaded for the purpose. In the lower partof the disk 17 are mounted two screws 19 20, provided with contact-nuts21 22. The battery 23 and the bell 24 are connected together andsuspended by means of the straps 16, as above stated. From the battery23 a Wire 25 leads to the contact-screw 19, and from the wire 25 anotherwire 26 leads to the contact-screw 20. The upper end of the strap 16 isprovided with a head 27, provided with ratchetteeth 28, which may beengaged by the pawl 13, as indicated by dotted lines in Figs. 1 and 2.The electric bell 24: is provided with a magnet 29. A switch 30 is usedfor opening and closing the circuit, so that the device may be throwninto or out of service, as desired. From the switch 30 a wire 31 leadsto the battery 23, and from the strap 16 a wire 32 leads to the vibrator35 of the bell. A wire 31 connects the contact member 33 of the switch30 with the magnet 29.

My invention is used as follows: The clamp 7 is placed upon the spindle6 of the knob 5 inside of the door, so as to be inaccessible from theexterior of the building. When therefore the spindle 6 is turned ineither direction, the plate 10 being rigid with the spindle is turnedangularly, as indicated in Fig. 2. As the spindle may be rocked ineither direction, it is obvious that the plate 10 may be turned todifferent angles. If now the device is to be thrown completely out ofservice, the switch 30 is simply opened and the pawl 13 is placed in theposition indicated in Fig.

1. If the alarm is to be used merely for purposes of announcing theopening of the door, the pawl ispla'ced in the position indicated byfull lines in Fig. 2. With the pawl in this position when the spindle 6is turned the strap 16 engages one or the other of the contact screws 1920, thereby completing the following circuitz'battery 23, wire 31,switch 30, wire 34:, magnet 29, vibrator 35, wire 32, strap 16,contact-screw 19 or 20, and wire 25 back to the battery 23, thuscompleting the circuit through the magnet 29 and ringing the bell. Asthe contact-nuts 21 22 are in metallic communication with thecontact-screws 19 20, they facilitate making contact with the strap 16that is to say, the strap 16 makes a sliding contact with thecontact-nuts and a directpressure contact with the contact-screws, sothat should the mechanical engagement between the strap and eithercontact-screw be imperfect a fairly good contact is nevertheless made bypressure upon the face of the contact-nut. The instant the spindle 6springs back to its normal position (indicated in Fig. 1) the circuit isbroken, the result being that the bell rings only so long as the knobremains turned by the torsional effect of the hand. When, however, it isdesired to use the device as a burglar-alarm, the pawl 13 is moved intothe position indicated by dotted lines in Fig. 1, the switch 30 beingclosed. If now the spindle (She turned, the pawl 13 drops into theposition indicated by dotted lines in Fig. 2, being engaged by theratchet-teeth 28, and thus preventing the disengagement of the strap 16and the contact-screw 19 or, at least, the contact-nut 21. By this meansthe bell is caused to ring continuously and is intended to have theeffect of frightening off the burglar, as well as of alarming the peopleliving upon the premises. The alarm is restored to its normal positionby merely raising the pawl into the position indicatedby full lines inFig. 1.

My invention admits of general use and is notlimited to application upondwellinghouses only. It may be employed in connection with safes,warehouses, and in all relations where a closure member is not to beopened except by giving warning.

I do not limit myself to the exact construction shown, for the reasonthat the operation of the device may be varied considerably withoutdeparting from the spirit of my invention.

Having thus described my invention, Iclaim as new and desire to secureby Letters Patent 1. An electric burglar-alarm, comprising a plate,means for connecting the same rigidly with the spindle of adoor-knob, amember mounted upon said plate and depending therefrom, contactmechanism connected with said plate and with said last-mentioned memberand actuated by movements of said plate for the purpose of opening andclosing an electric circuit, and an electric bell mounted upon saidmember and energized by said circuit.

2. In an electric burglar-alarm, the combination of a plate, means forconnecting the same rigidly with the spindle of a door-knob so that saidplate is turned to divers angles by movements of said door-knob, amember connected with said plate and depending therefrom, a contact tobe opened and closed by movements of said member, and a pawl for lockingsaid member and said plate in a predetermined relative position for thepurpose of keeping said contact closed continuously after said plate hasbeen moved.

8. An electric burglar-alarm, comprisinga spindle to be rotated bymovements of a knob,

5 a plate rigidly connected with said spindle and provided with acentral slot and with an ancillary slot, a pawl connected with saidplate and movable relatively to both of said slots, a member connectedwith said plate and provided with a ratchet, means for normallymaintaining said ratchet in a predetermined position relatively to thehorizon, and a contact to be closed by relative movements between saidplate and said member.

' 4:. In an electric burglar-alarm, the com bination of a plate providedwith means for connecting the same to a spindle, and also pro vided witha slot, a pawl connected with said plate and movable along said slot,means for temporarily supporting said pawl in a predetermined positionrelatively to said plate and independently of said slot, a ratchet to beengaged by said pawl when said plate is turned, said ratchet being forthe purpose of maintaining said plate in a predetermined positionrelatively thereto, contact mechanism connected with said ratchet andadapted to be opened and closed thereby, and alarm mechanism connectedwith-said contact mechanism.

5. In an electric burglar-alarm, the combination of a plate providedwith means for connecting the same to a spindle, a member connected withsaid plate and depending therefrom, an electric bell mounted upon saidmember, contact mechanism connected with said plate and adapted to beopened and closed by movements thereof, an electric circuit extendingfrom said contact mechanism to said electric bell, and amanually-operated switch for opening and closing said electric circuit.

6. In an electric burglar-alarm, the combination of a member to beconnected rigidly upon a spindle and to be turned to different angles bymovements thereof, contact mechanism mounted upon said member and openedand closed by movements thereof, electric circuits connected with saidcontact mechanism, and a bell included within said circuit and energizedthereby.

7. In an electric burglar-alarm, the combination of a plate, means forsecuring the same rigidly upon a spindle, a pin mounted within saidplate, a strap pivotally mounted upon said pin and adapted to supportthe weight of a battery and an electric bell, a contact member to beengaged by said strap, and wiring connected with said strap and withsaid contact member, said wiring being further connected with saidbattery and with said electric bell.'

8. In an electric burglar-alarm, the combination of a spindle, a platerigidly connected therewith and adapted to be turned to differentangles, said plate being provided with a central slot and with, anancillary slot disposed at an angle to said central slot and mergedthereinto, a pawl having substantially the form of a dumb-bell andslidably mounted within said slots so as to be movable from one of saidslots to the other, a ratchet to be engaged by said pawl, contactmechanism con-- nected with said ratchet and adapted to be opened andclosed by movements of said plate relatively to said ratchet, andelectric mechanism connected With said contact mechanism for the purposeof sounding an alarm.

9. In an electric burglar-alarm, the combination of a member to beconnected rigidly with the spindle of a door-knob, a comparatively heavymember journaled upon said firstmentioned member and free to move todifierent angles relatively thereto, a battery and a bell mounted uponsaid second mentioned member and adding their weight thereto so thatsaid member provided with said bell and with said battery depends fromsaid first-mentioned member, and contact mechanism to be scribingWitnesses.

AMOS GETTO. Witnesses: 1

GEORGE W. TRIOE, RICHARD Rorr.

